METABOLISM IN THE NORMAL FUNCTIONAL STATE 27 



2 4 6, 8 10 12 



Time offer adminisfrafion (hr) 



Fic. 4. The incorporation of radioactive phosphate into 

 individual phospholipids of rat and mouse brain. Data from 

 Dawson and Richter (1950) ; Dziewiatkowski and Bodian (1950) ; 

 Ansell and Dohmen (1958). O = cephalin diphosphoinositide; 

 A = phosphatidyl choline; D = phosphatidyl serine; x = 

 phosphatidyl ethanolamine ; • = total phospholipids. Specific 

 activity == counts/min per /xg phosphorus. 



phosphoinositide which exchanges its phosphorus rapidly (Hokin 

 and Hokin, 1958<3). It is likely that other phosphoHpids of similar 

 metabolic character will be discovered as separative techniques 

 improve. In this connexion the presence of phosphatidic acids, 

 apparently localized in the microsomes, have been demonstrated 

 in guinea pig brain (Hokin and Hokin, 19586). These acids 

 have also been found to exchange appreciable quantities of 

 radioactive phosphorus in vivo. 



Incorporation into Phosphoproteins, Nucleic Acids and Residual 

 Organic Phosphates 



Knowledge of phosphorus metabolism in these groups of 

 compounds is still meagre. The incorporation of radioactive 

 phosphorus, administered either by intravenous or by intra- 

 cisternal injection is most rapid into the phosphoprotein fraction 



